It is well known in the manufacturing industries, such as the auto industry, to form a sheet metal panel in a stamping process where the sheet metal panel is pressed between a pair of dies to assume a complex three-dimensional shape. A sheet metal blank is typically cut from a coil of material. The sheet metal material is chosen for its desirable characteristics, such as thickness of the metal, alloy of the metal, surface coating on the sheet metal, etc.
It is also known in the manufacturing industries to create a tailor welded blank by welding together two separate sheet metal blanks having different characteristics. For example, in the manufacture of a door inner panel, it may be desirable to have a first portion of the door inner panel constructed of a galvanized sheet metal of a certain gauge to provide requisite corrosion resistance and high strength. Another portion of the door inner panel may be made of a lighter gauge of metal with no galvanized coating.
Accordingly, tailor welded blanks have been manufactured by first creating two separate blanks of the sheet metal materials having the different characteristics, and then butting the edges of the two sheets together and welding the adjoining edges of the sheets to create a permanent attachment. In this way, a blank assembly is created that is comprised of the two different sheet materials having different characteristics. This blank assembly, known as a tailor welded blank, is then processed through the conventional stamping or other metal forming processes. Thus, the finished product, such as a door inner panel, will have different portions of the finished product having different sheet metal characteristics.
Because the portions of the blank assembly have sheet metal of different characteristics, the different regions of the blank assembly may react differently during the forming process and may perform differently in the finished product after forming as a finished product. For example, adjoining regions, once subjected to a welding process such as laser welding, may exhibit different microstructures and as a consequence may exhibit different mechanical properties from one another. Thus in the forming process the different portions of the part will behave differently under the deformation that occurs during the forming process, and there may be a non-uniform strain distribution in the finished part.